Fix gate-opening vibration by pulsing instead of one long effect

Siim reported the hit-vibration works but the lobby gate's rumble
doesn't. Godot's start_joy_vibration() docs call this out directly:
long single effects are unreliable on much gamepad hardware/drivers,
and recommend a short effect repeated instead. Added
Controls.vibrate_for() to do that and pointed the gate at it in place
of its single 7-second call.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MXBNaEBmrYDSMcv4NgUWtV

levels/lobby_underground.gd

@@ -11,4 +11,4 @@ func _process(_delta: float) -> void:
 	if Run.bear_gate_open() or DP.b("gate_unlocked_bear"):
 		bear_gate_open = true
 		$AnimationPlayer.play("Gate_opening")
-		Controls.vibrate(0, 0.5, .5, 7)
+		Controls.vibrate_for(0, 0.5, .5, 7.0)